The present invention relates to an apparatus and a method for information processing and a recording medium, and particularly to an apparatus and a method for information processing and a recording medium that can reencode video data more efficiently.
Digital television broadcasts such as DVB (Digital Video Broadcast) in Europe, DTV (Digital Television) broadcast in the U.S., and BS (Broadcast Satellite) digital broadcast in Japan use an MPEG (Motion Picture Expert Group) 2 transport stream. The transport stream is formed by a series of transport packets. The transport packet is packetized video data or audio data, for example. Data length of a single transport packet is 188 bytes.
Digital television broadcasts are different from analog television broadcasts in that a digital television broadcast can provide service with multimedia coding data. This service associates video data, audio data, character and pattern data, still image data, and other data with each other by the multimedia coding data and transmits the data. In the case of the BS digital broadcast of Japan, for example, an XML (Extensible Markup Language)-based coding method is used for the multimedia coding data. Details of this method are disclosed in ARIB STD-B24 Data Coding and Transmission Specification for Digital Broadcasting, for example.
Video data, audio data, character and pattern data, still image data, and other data are transmitted as transport packets.
If a television program transmitted as a so-called transport stream in a digital television broadcast is recorded as it is received, it is possible to record the television program without degrading its image quality and sound quality. In some cases, however, it is desired to record as long a television program as possible on a recording medium having a limited capacity, even if its image quality, for example, is somewhat degraded. In such cases, a video stream may be reencoded to lower its bit rate, for example.
The bit rates of the video stream and other streams may be lowered at the same rate. For example, when the bit rate of an input transport stream is lowered to ½ for output, the bit rate of its video stream is lowered to ½, and also the bit rate of streams other than the video stream is lowered to ½. As a result, a stream other than the video stream with a relatively low data volume, in particular, for example, an audio stream, is greatly affected, which results in great degradation in sound quality.